Bacterial cellulose in cyanobacteria : enhancement of cellulose production in Synechococcus elongatus with Gluconacetobacter xylinus transgenes

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Abstract

Bacterial cellulose produced by Gluconacetobacter xylinus possesses an abundance of desirable properties which allow for commercial applications in manufacturing, construction, medicine, as a biofuel feedstock and in electronics as an electrical insulator. Large scale production methods are currently limited by expensive media and requirements for sterile conditions. This thesis investigates the potential for using cellulose synthesized by cyanobacteria as an alternative. Cyanobacteria require fewer media components, fix atmospheric carbon dioxide, and some species fix atmospheric nitrogen, reducing the demand for fertilizer and lowering contamination potential. In this study, a suite of genes involved with cellulose synthesis in G. xylinus were successfully transferred to into the unicellular cyanobacterium, Synechococcus elongatus. Cellulose synthesis was increased in multiple transgenic strains by 300-400% and cellulose microfibrils were observed with enhanced crystallization upon addition of the acsCD transgene from G. xylinus. The evolutionary history of the proteins involved in cellulose synthesis was also investigated, with particular interest paid toward the catalytic subunit. It was determined that all current organisms with the capability of cellulose assembly possess synthases from a single ancestral origin at least 2.5 billion years ago. This work provides additional support to the theory that vascular plants acquired cellulose synthases from cyanobacteria.